Bad Math and Construction

I was recently in a client's office that was having some equipment related issues in their men's bathroom. This involved some ceiling and wall alteration. While I was in the bathroom at one point I noticed this where some wall tile had been removed.

The correction is mine (red rectangle), in pencil naturally, I don't want to be accused of vandalism!

The last time I checked a calculator 40 + 56 = 96, not 106. When you add 29 to 96 you get 125, not 135. At least the harder multiplication of 14 x 4 = 56 is correct. I'm terrible at math...really bad...but even I caught this error. That's really bad when Mr. OpEd catches your math error!!

Well, maybe they were just building in a percentage for waste?